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<title> Multimedia Group Current Research</title>

<H1> Research Agenda </h1>

<h2> Vision </h2>

<p> Since the debut of the first usable computer almost half a century
ago, the world has witnessed dramatic improvements in computer and
communications technologies. Whereas breakthroughs in computer
technology have stimulated the integration of digital continuous media
(such as audio and video) with computing, rapid advances in
communication technology have made available high-bandwidth,
fiber-optic networks at modest cost. The synergy between the advances
in computer and communications technologies promises to create an
infrastructure for designing information management systems in a wide
range of application domains.

<p> The functionality and the performance attained by most of the
existing information management systems, however, are insignificant as
compared to their potential capability. We believe that the reasons
for this limitation stem in part from the fact that, traditionally,
researchers and developers have almost exclusively focussed on
individual aspects of system design and application development.
Consequently, very little attention has been devoted towards designing
an integrated system architecture that can efficiently support modern
applications (which may involve text, audio, video, images, animation,
etc.). Attaining a breakthrough in designing and evaluating such
system architectures, however, will require orchestrating a coherent
and comprehensive effort that integrates expertise in media
compression, information storage and retrieval, database systems,
high-speed networking, and systems engineering. The main goal of the
Distributed Multimedia Computing Laboratory is to facilitate such
broadly-based research and to provide an excellent environment for
integrating research work on various aspects of high-performance
networked multimedia systems.

<h2> Current Research </h2> 

The main research projects currently underway in the Distributed
Multimedia Computing Laboratory are: (1) design and implementation of
a multimedia storage server and (2) development of network and transport
protocols for digital audio and video. 

<ul> 

<li> <b> Design and implementation of multimedia storage servers: </b>
In this project, we are developing methods for efficient placement and
retrieval of digital media streams from disk arrays. Our placement
policies exploit: (1) the sequentiality of media playback to maximize
the disk array throughput during retrieval, and (2) the inherent
redundancy in video streams (rather than error-correcting codes) to
recover from disk failures. Our retrieval techniques, on the other
hand, exploit the human perceptual tolerance to maximize the
utilization of the server resources. The admission control algorithms
that we have developed make it possible to provide deterministic,
statistical, and predictive service guarantees to clients, thereby
addressing the heterogeneous quality of service requirements of
clients. We are currently investigating techniques for efficiently
supporting interactive control operations (such as fast-forward and
rewind) as well as methods for enhancing the scalability of the
multimedia servers. A prototype multimedia storage server that
instantiates the results of our research is being implemented in the
laboratory. <p>

<li> <b> Network and transport protocols for digital audio and video:
</b> In this project, we are developing channel admission procedures,
bandwidth allocation policies, and scheduling disciplines that are
optimized for supporting media communication from multimedia servers
to client sites. We are investigating the utility of employing
guaranteed rate scheduling algorithms in conjuction with traffic
shaping mechanisms for efficient delivery of video and audio streams
from a multimedia server to client sites. We are also investigating
feedback-based protocols for video communication over high-speed
networks. Finally, we are developing resource reservation and routing
algorithms. We believe that these algorithms will lay the foundation
for addressing the heterogeneity in the computing and networking
infrastructures as well as the diversity in the quality of service
requirements of clients in the multimedia computing infrastructures of
the future.

</ul> 

<p> Since we believe that many of the important and difficult research
issues are likely to be ignored without an ambitious implementation
plan, we are currently instantiating our research findings by
designing and implementing an <i> integrated multimedia file system
</i>. Such a prototype implementation will not only validate our
system design, but will also form the basis of transferring technology
from academic environment to commercial and federal institutions. <p>

<hr>

<p> If you are interested in receiving detailed information about the
specifics of the research activities in the laboratory, please send a
mail to Professor Harrick Vin (vin@cs.utexas.edu). <p>

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